Salvia miltiorrhiza (S. miltiorrhiza) root contains several compounds that have a variety of physiological effects such as anti-oxidant, anti-cancer, anti-atherosclerotic, anti-inflammatory and anti-bacterial activities. S. miltiorrhiza contains diterpenoid compounds such as tanshinone Ⅰ, ⅡA and cryptotanshinone and phenolic compounds such as salvianolic acids A, B and C. The contents of major compounds, tanshinone ⅡA and cryptotanshinone, from S. miltiorrhiza were quantitatively analyzed by using high performance liquid chromatography (HPLC) to find the optimal extraction condition after the simultaneous analysis method was validated. The ROS and ONOO^- scavenging assays were performed to evaluate the anti-oxidant effect of ethanol extracts from S. miltiorrhiza prepared by different extraction methods and solvents as well as tanshinone ⅡA and cryptotanshinone. The contents of tanshinone ⅡA and cryptotanshinone in extracts of S. miltiorrhiza by extraction method were the highest in immersion method with 12.255% and 7.626%. And the contents in ethanol extracts by extraction solvent were the highest in 100% ethanol with 12.407% and 8.216%. The optimized extraction condition of S. miltiorrhiza with the highest concentration of tanshinone ⅡA and cryptotanshinone was the immersion extraction method with 100% ethanol. The results showed that S. miltiorrhiza extracts by different extraction methods and solvents as well as tanshinone ⅡA and cryptotanshinone significantly have the anti-oxidant effects in a dose-dependent manner, indicating that tanshinone ⅡA and cryptotanshinone are effective major compounds for the anti-oxidation in S. miltiorrhiza. These results can be used as basic data for the standardization of products from S. miltiorrhiza and tanshinone ⅡA and cryptotanshinone can be expected to be a candidate for anti-oxidant health functional foods and herbal medicines.